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JWST Full Mirror
The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This will enable investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. The U.S. National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development, the Space Telescope Science Institute in Baltimore on the Homewood Campus of Johns Hopkins University operates JWST, and the prime contractor was Northrop Grumman. The telescope is named after James E. Webb, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Observatory
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launched in 1968, and the Soviet Orion 1 ultraviolet telescope aboard space station Salyut 1 in 1971. Space telescopes avoid the filtering and distortion ( scintillation) of electromagnetic radiation which they observe, and avoid light pollution which ground-based observatories encounter. They are divided into two types: Satellites which map the entire sky (astronomical survey), and satellites which focus on selected astronomical objects or parts of the sky and beyond. Space telescopes are distinct from Earth imaging satellites, which point toward Earth for satellite imaging, applied for weather analysis, espionage, and other types of information gathering. History Wilhelm Beer and Johann Heinrich Mädler in 1837 discussed the advantages of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korsch Telescope
A three-mirror anastigmat is an anastigmat telescope built with three curved mirrors, enabling it to minimize all three main optical aberrations – spherical aberration, coma, and astigmatism. This is primarily used to enable wide fields of view, much larger than possible with telescopes with just one or two curved surfaces. A telescope with only one curved mirror, such as a Newtonian telescope, will always have aberrations. If the mirror is spherical, it will suffer from spherical aberration. If the mirror is made parabolic, to correct the spherical aberration, then it must necessarily suffer from coma and off-axis astigmatism. With two curved mirrors, such as the Ritchey–Chrétien telescope, coma can be minimized as well. This allows a larger useful field of view, and the remaining astigmatism is symmetrical around the distorted objects, allowing astrometry across the wide field of view. However, the astigmatism can be reduced by including a third curved optical element. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommand
A telecommand or telecontrol is a command sent to control a remote system or systems not directly connected (e.g. via wires) to the place from which the telecommand is sent. The word is derived from ''tele'' = remote (Greek), and ''command'' = to entrust/order (Latin). Systems that need remote measurement and reporting of information of interest to the system designer or operator require the counterpart of telecommand, telemetry. The ''telecommand'' can be done in real time or not depending on the circumstances (in space, delay may be of days), as was the case of Marsokhod. Examples *Control of a TV from the sofa *Remote guidance of weapons or missiles *Control of a satellite from a ground station *Flying a radio-controlled airplane Transmission of commands For a Telecommand (TC) to be effective, it must be compiled into a pre-arranged format (which may follow a standard structure), modulated onto a carrier wave which is then transmitted with adequate power to the remote sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telemetry
Telemetry is the in situ data collection, collection of measurements or other data at remote points and their automatic data transmission, transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek language, Greek roots ''tele'', "remote", and ''metron'', "measure". Systems that need external instructions and data to operate require the counterpart of telemetry, telecommand. Although the term commonly refers to wireless data transfer mechanisms (e.g., using radio, ultrasonic, or Infrared#Communications, infrared systems), it also encompasses data transferred over other media such as a telephone or computer network, optical link or other wired communications like power line carriers. Many modern telemetry systems take advantage of the low cost and ubiquity of GSM networks by using SMS to receive and transmit telemetry data. A ''telemeter'' is a physical device used in telemetry. It consists of a sensor, a transmission path, and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S Band
The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), wireless networking (WiFi), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens (typically at 2.495 GHz). India's re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunshield (JWST)
The James Webb Space Telescope (JWST) sunshield is a passive thermal control system deployed post-launch to shield the telescope and instrumentation from the light and heat of the Sun, Earth, and Moon. By keeping the telescope and instruments in permanent shadow, it allows them to cool to their design temperature of . Its intricate deployment was successfully completed on January 4, 2022, ten days after launch, when it was more than away from Earth. The JWST sunshield is about , roughly the size of a tennis court, and is too big to fit in any existing rocket. Therefore, it was folded up to fit within the fairing of the launch rocket and was deployed post-launch, unfolding five layers of metal-coated plastic. The first layer is the largest, and each consecutive layer decreases in size. Each layer is made of a thin (50 microns for the first layer, 25 microns for the others) Kapton membrane coated with aluminum for reflectivity. The outermost Sun-facing layers have a doped- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Bus (JWST)
The spacecraft bus is the primary support element of the James Webb Space Telescope, launched on . It hosts a multitude of computing, communication, propulsion, and structural components. The other three elements of the JWST are the Optical Telescope Element (OTE), the Integrated Science Instrument Module (ISIM) and the sunshield. Region 3 of ISIM is also inside the spacecraft bus. Region 3 includes the ISIM Command and Data Handling subsystem and the Mid-Infrared Instrument (MIRI) cryocooler. The spacecraft bus must structurally support the 6.5 ton space telescope, while weighing only . It is made primarily of graphite composite material. It was assembled in the U.S. state of California by 2015, and then it had to be integrated with the rest of the space telescope leading up to its planned 2018 launch. The bus can provide pointing precision of one arcsecond and isolates vibration down to two milliarcseconds. The fine pointing is done by the JWST fine guidance mirror, obviating t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Telescope Element
Optical Telescope Element (OTE) is a sub-section of the James Webb Space Telescope, a large infrared space telescope launched on , consisting of its main mirror, secondary mirrors, the framework and controls to support the mirrors, and various thermal and other systems. The OTE collects the light and sends it to the science instruments in Webb's Integrated Science Instrument Module. The OTE has been compared to being the " eye" of the telescope and the backplane of it to being the " spine". The primary mirror is a tiled assembly of 18 hexagonal elements, each from flat to flat. This combination yields an effective aperture of and a total collecting surface of . Secondary mirrors complete anastigmatic imaging optics with effective 20 focal ratio and focal length of . The main three-mirror telescope is a Korsch-type design, and it feeds into the Aft Optics Subsystem (part of OTE), which in turn feeds into the Integrated Science Instrument Module which holds the science instr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Science Instrument Module
Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope, a large international infrared space telescope launched on . ISIM is the heart of the JWST, and holds the main science payload which includes four science instruments and the fine guidance sensor. ISIM is the spacecraft chassis and instruments that take the light from the main mirror and convert that into the science data that is then sent back to Earth. The other two major sections of the JWST are the Optical Telescope Element (OTE) (mirrors and their structure) and the Spacecraft Element (SE), which includes the spacecraft bus and sunshield. ISIM has a mass of 1400 kg (3086 lb), about 23% of the mass of the JWST. The infrared camera instrument integrated with ISIM passed its thermal tests in early 2016. ISIM underwent intense thermal cold testing in late 2015 to early 2016. NIRcam is extremely important to JWST, because it's not only a sensitive infrared camera, but it is also us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NIRSpec
The NIRSpec (Near-Infrared Spectrograph) is one of the four scientific instruments flown on the James Webb Space Telescope (JWST). The JWST is the follow-on mission to the Hubble Space Telescope (HST) and is developed to receive more information about the origins of the universe by observing infrared light from the first stars and galaxies. In comparison to HST, its instruments will allow looking further back in time and will study the so-called Dark Ages during which the universe was opaque, about 150 to 800 million years after the Big Bang. The NIRSpec instrument is a multi-object spectrograph and is capable of simultaneously measuring the near-infrared spectrum of up to 100 objects like stars or galaxies with low, medium and high spectral resolutions. The observations are performed in a 3 arcmin × 3 arcmin field of view over the wavelength range from 0.6 µm to 5.0 µm. It also features a set of slits and an aperture for high contrast spectroscopy of individual sources, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NIRCam
NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other words, it is a camera and is also used to provide information to align the 18 segments of the primary mirror. It is an infrared camera with ten mercury-cadmium-telluride (HgCdTe) detector arrays, and each array has an array of 2048×2048 pixels. The camera has a field of view of 2.2×2.2 arc minutes with an angular resolution of 0.07 arcsec at 2 microns. NIRCam is also equipped with coronagraphs, which helps to collect data on exoplanets near stars. It helps with imaging anything next to a much brighter object, because the coronagraph blocks that light. NIRCam is housed in the Integrated Science Instrument Module (ISIM), to which it is attached by struts. It is designed to operate at , so it can detect infrared radiation at this wavelength. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MIRI (Mid-Infrared Instrument)
MIRI, or Mid-Infrared Instrument, is an instrument on the James Webb Space Telescope. MIRI is a camera and a spectrograph that observes mid to long infrared radiation from 5 to 28 microns. It also has coronagraphs, especially for observing exoplanets. Whereas most of the other instruments on Webb can see from the start of near infrared, or even as short as orange visible light, MIRI can see longer wavelength light. MIRI uses silicon arrays doped with arsenic to make observations at these wavelengths. The imager is designed for wide views but the spectrograph has a smaller view. Because it views the longer wavelengths it needs to be cooler than the other instruments (see Infrared astronomy), and it has an additional cooling system. The cooling system for MIRI includes a Pulse Tube precooler and a Joule-Thomson Loop heat exchanger. This allowed MIRI to be cooled down to a temperature of 7 kelvins during operations in space. Overview The spectrograph can observe wavelengths be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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